Polymers as a class of materials are generally flammable. Considerable attention has been given the development of materials for incorporation into polymers to render them flame retardant.
A wide variety of phosphorus and halogen containing compounds have been shown in the prior art to impart flame retardancy to polymers, however, there are usually problems attendant the use of these materials. One source of difficulty for the incorporation of flame retardants relates to modern methods of hot milling polymer compositions. In hot milling techniques, the polymer is extruded with a heated screw mechanism, typically at temperatures above 210.degree. C. and often as high as 390.degree. C. Under these high temperature conditions both thermosetting and thermoplastic materials become workable and permit uniform inclusion of additional agents such as flame retardants. Unfortunately, flame retardants often participate in decomposition or side reactions which impart undesirable odor or color to the base polymer being processed. Other flame retardants become somewhat volatile under processing conditions and are not effectably retained during processing.
It is desirable to develop new flame retardant agents which are thermally stable, essentially non-volatile, and adaptable to high temperature milling technology.